In eye medicine, both during diagnosis and therapy, light is frequently used. This can be particularly provided, since the eye is mostly transparent and can be reached by rays of light, practically in its entirety. Hereinafter, light must be understood as the entire visible spectrum from ultraviolet to infrared emissions.
Slit lamps, eye-fundus cameras and laser scan ophthalmoscopes are particularly well known diagnostic devices which work with light.
A slit lamp produces a variable light section by means of a gap picture projection in the eye, with which conclusions may be obtained depending on the condition of the individual media of the eye. Usually the slit images are produced mechanically by means of the width and length of the variable gap. From patent DE 101 51 314, whose entire contents is incorporated by reference, a well-known light section may also be produced by means of an appropriate light distribution from DMDs (digital Mirror devices), LED (Light Emitting Diode), LCD (Liquid Crystal display) or OLEDs (Organic Light Emitting Diodes) for developed micro displays. What all of these light sources have in common is that they permit only a relatively small image frequency, since they show either mechanically moved parts (DMD) or long image retention.
With a fundus camera, such as the one known from patent DE 298 08 351 U1, the eye background is illuminated with a classical light source like a halogen or a mercury vapor lamp and afterwards a photographic or digital image of the retina is produced. It is also widely understood that these photographs can only be taken in certain spectral areas, in order to cause fluorescence of molecules in interest, which is produced by means of appropriate lighting. For special purposes, flash photographs are also taken in order to recognize quickly occurring processes. However additional photo flash lamps are necessary, which must be linked over the appropriate additional optics into the path of rays. Also, these flash lamps have a limited field rate.
With a laser Scan ophthalmoscope, such as the one described in patent DE 198 35 967 C2, the inside of the eye is scanned by means of a 2 or 3 dimensional mechanical scanner with positioned laser beam and arising fluorescence is detected. Because of the mechanical movement of the scanners, the picture recording frequency is limited in this case, so that rapid procedures cannot be pursued, in addition to which geometrical disturbances are produced in the contents of the resulting picture due to the involuntary movements of the eye. Light-based therapy devices are likewise well known in eye medicine. Thus, treatment of visual defects by means of laser radiation removing material from the cornea may be done with equipment such as the one described in patent WO 01/66029, whose complete contents are incorporated by reference. The beam of a treatment laser is guided by means of a mechanical scanner which has moving mirrors, purposefully placed across the treatment area. The mechanics of the scanner are also here the limiting factor for increasing the treatment speed and thus to reduce the treatment time.
The involuntary eye movements, which arise during treatment, lead to deviations between the intended and the actual place of the material removal. The resulting errors can be avoided by using an eye tracker, which detects the momentary position/line of sight of the eye, so that it can recognize these movements. These movements are then taken into account during the control of material removal and thus balanced.
In U.S. Pat. No. 6,179,422, whose entire contents are incorporated by reference, such an eye tracker is described, which for its part leads an IR laser beam quickly across the pupil of the eye and the eye limbus by means of such a scanner. The reflected radiation is detected by means of a fast photodiode and the movement of the eye can be determined from the contrast shifts of the pupil flanks and the eye limbus between individual scans. This solution is also limited by the accuracy and speed of the mechanical scanner.
The invention is also applicable in other procedures for the investigation of biological objects such as confocal microscopy, for example.
From patent EP 485803 B1, all contents of which are incorporated by reference, a con-focal microscope is well known, which uses a LED or a LCD array for lighting the sample and analyzes the lighted sample by means of a detector array. Therefore, this microscope is not suitable for the examination of quick procedures. Also, for example, laser scanning microscopes, known from patent DE 197 33 195 A1, use mechanical scanners to deflect laser beams used for lighting the sample and are, therefore, likewise not suitable for the investigation of very fast procedures. However, only in recent years the interest in the investigation of extremely fast molecular reciprocal effects in biology has substantially risen.